My friend and I are new to pinball repair and we are looking for a little help. Here is the situation. We have a firepower II Williams system 7 that is burning the switch matrix chip starting at IC18 and causing the chip to smoke as soon as we power up. BTW, brand new set of Kohout boards are installed. We were told this indicates a short of either lamp or solenoid getting into the switch circuit. In the process of testing with the J2 disconnected we had a flipper activating which we were told look at the main harnesses and check if they are reversed. Sure enough they were black connector was hooked to white. So that stopped the flipper for activating. Could the reversed harnesses also cause the switch matrix burning??? We were told to check Pin and and 9 so column 1 and 2 of the switches. We have check them multiple times and we can't see a short. We have also put a meter on all the green wire is J2 harness and non are showing voltage. So was the problem the reversed harness all along or do we keep looking before we attempt to plug matrix back in and smoke the chips again? Any help would be great. THANKS!

Thanks for the response.
I know the basics of reading schematics but I get lost sometimes when it gets complex. The harnesses being backward definitely cause major issues sending improper voltage all over the place. The switch matrix problem is resolved but it appears we also have MPU damage as the machine doesn't boot up. We are waiting to hear back from Kohout about what may have been damaged on there board. We are hoping it will just be a chip swap as all there chips are socketed. Major lesson learned here though. We are kicking ourselves for not checking those harnesses. We would have never thought to check them or think they were interchangeable like that as the machine was together when we got our hands on it.

never even knew that a harness could be put on backwards
usually they have a slot or two on them making that impossible
check all of them then just to make sure none of the others are screwed up
good luck and keep us posted on it

with reversed wire harness jacks , damaging voltages may have been sent to all chips on all boards. with the jack problem fixed, and everything else checks out fine, i would say replace the switch matrix chips and see what happens. check if there is still any warranty left on boards for repair or replacement if matrix repair isnt the only issue.